Mewtwo was released at Pikachu Outbreak, an annual festival in Yokohama, Japan, where two million players caught 120 million monsters.

Unlike its previous big event, the disastrous Pokemon Go Fest in Chicago, the Pikachu Outbreak event was a huge success, foreshadowing big things for "Pokémon Go" in the United States and elsewhere.

Way back in September 2015, the very first trailer for "Pokémon Go" hinged on one completely irresistible image: Hundreds of Pokémon trainers teaming up to take down Mewtwo, a legendary and very popular monster.

When the game launched in June 2016, however, Mewtwo was nowhere to be found. In fact, "Pokémon Go" players didn't even get the opportunity to team up to collect powerful, legendary monsters until a sweeping update earlier this summer.

Niantic says that in the seven days of the Pikachu Outbreak, two million players caught 120 million Pokémon. Niantic says, too, that it worked with local cell phone companies to make sure that there was enough network capacity, and the resulting event was way more successful than the disastrous Pokémon Go Fest in Chicago.

An outbreak of Pikachu

You can read an on-the-ground account of the Mewtwo event at The Verge. The short version is that it was apparently a little anticlimactic — with so many players fighting Mewtwo, the monster went down in no time. And every player caught Mewtwo on their first try. Still, it was the biggest group event ever held by "Pokémon Go."

For Pikachu Outbreak, Niantic and The Pokémon Company coordinated to turn the city of Yokohama into a huge "Pokémon Go" play area, with rare monsters like Larvitar, Unown, and a shiny variant of Pikachu dispersed all over the city and its environs.

A family celebrates getting Mewtwo at the Pikachu Outbreak event.
Niantic

The centerpiece of the event, though, was the chance to capture Mewtwo.

Ahead of the event, players had to enter a lottery for the chance to enter a local stadium for the chance to battle the mythical monster. Every 15 minutes, a huge group of players were shuttled in to battle the monster en masse, with the occasion marked by a projection of Mewtwo on the scoreboard and special fireworks at the culmination. All in all, "thousands" participated, says Niantic.

Soon, so-called "exclusive raids" will be coming to the United States, giving domestic players their own chances to catch Mewtwo. Those raids will be invite-only, leading big groups of players to the same place at the same time for, hopefully, their own epic battles.

Whether or not those events match the scale and scope of that original trailer remains to be seen. But Niantic is finally delivering on the game's original promise, bringing us closer and closer to the "Pokémon Go" we've been waiting for. And, hey, if the first time out was anticlimactic, now Niantic can build something better next time.

Now, if the game just adds player-versus-player battling and Pokémon trading, we'll really be set.